Conduct an effectiveness trial of a school-based cardiovascular disease (CVD) prevention intervention over a 3 year period to study the diffusion potential of the program. Specific Aims: students who receive our CVD prevention curriculum taught by teachers trained via specialized computer software will demonstrate: (a) significantly greater knowledge about CVD risk factor processes than students in a no-treatment control condition, (b) significantly greater self-reported increase in aerobic physical activity; greater self-reported decrease in consumption of fat intake and a higher cessation rate among experimental smokers than students in a no-treatment control condition, and (c) significantly greater decreases in resting heart rate than students in a no-treatment control condition. Having previously established the efficacy of our prevention curriculum we now propose a large scale effectiveness trial with a specific focus on the implementation and maintenance aspects of diffusion. Diffusion may be the most critical problem for school health education. Research on program diffusion has tended to focus on the adoption and dissemination stages. Considerably less effort has been devoted to determining whether and how curricula get used in classrooms. Yet, failure to plan for effective implementation is often the major reason new programs fail. In order to promote implementation and maintenance, we will couple our CVD prevention curriculum with a computer-based teacher training program (CAI) developed and tested in a previous study. The software provides teachers with an in-depth knowledge of the content of the intervention and was very well received by regular teaching staff in the previous trial. However, teacher training is but one important form of implementation and maintenance intervention. In the proposed study we will include additional implementation intervention components in order to strengthen the diffusion potential of our CVD prevention curriculum. Design: Ten high schools (N = approximately 5400) will participate in the study. The schools will be randomly assigned to intervention on no-treatment control conditions. Student Outcome Measures: will include self-reported cigarette smoking, physical activity and eating behavior, problem behaviors, heart rate, height and weight, school performance and attendance. Implementation process measures include: quantity and quality of the implementation. Teacher and Organizational Factors to be measured include: implementation self-efficacy, comfort, preparedness, perceived principal encouragement, program acceptance, principal encouragement and principal's beliefs about the program. The effect sizes of interest to the study proposed lie in the 0.20 to 1.00 range. For the Treatment Effect, with a sample size of over 5000 students, there is better than 99% power of detecting an effect size as small as 0.07 using a 2 tailed 1 % level test. The large sample size is necessary for purposes of determining targeting issues, process issues etc. all important for assessing the policy repercussions of these findings.